The pharmacological action
Antiviral drug, especially effective against herpes simplex virus (the virus that causes lesions of the skin and mucous membranes) and herpes zoster (the virus that causes disease of the central and peripheral nervous system with the emergence of bubble rash along the sensory nerves).
Acyclovir is an analog of a purine nucleoside dezoksiguanidina, the normal component of the DNA (deoxyribonucleic acid – part responsible for the transfer of genetic information of the cell nucleus).
The similarity of structures and acyclovir acyclovir dezoksiguanidina allows to interact with the viral enzymes, which leads to an interruption of viral replication. After the introduction of acyclovir in herpes diseased cell under the influence of thymidine released virus aiiklovir converted to acyclovir monophosphate which enzymes of the host cell is transformed into acyclovir diphosphate. and then to the active form of acyclovir-triphosphate, which blocks viral DNA replication (intracellular mechanism DNA complex division, resulting in the multiplication of viruses). The drug acts selectively on viral DNA synthesis. DNA of the host cell replication (human cells) to acyclovir triphosphate has almost no effect.
When administered acyclovir absorbed only partially (approximately 20%). The half-life (the time for which the output ‘/ zyaozy drug) by ingestion and administered intravenously for about 3 hours. Provided mainly kidneys unchanged, partly in the form of a metabolite (exchange product). In renal insufficiency, the half-life is greatly increased (up to 19.5 hours).
Dosing and Administration
– in the treatment of infections of the skin and mucous membranes caused by Herpes simplex (types 1 and 2), for adults and children over 2 years of age – 200 mg 5 times per day for 5 days at intervals of 4 hours during the day and at intervals of 8 h at night (the course can be extended if necessary).
– for preventing recurrence of infections caused by Herpes simplex (types 1 and 2), and at relapse of disease -. 200 mg 4 times a day every six hours duration of prophylactic administration is determined by the duration period of risk.
– in the treatment of infections caused by Varicella zoster, adults appoint 800 mg 5 times a day every 4 hours during the day and at intervals of 8 hours at night. Duration of treatment – 7 days. Treatment of chickenpox in immunocompetent patients should begin within 24 hours after onset of the rash.
– under severe condition in immunocompromised patients (e.g., after bone marrow transplantation), or patients with impaired absorption from the gut is preferable to use intravenous acyclovir.
The incidence of side effects is given in the following grading: very often (≥1 / 10); often (≥1 / 100, <1/10); uncommon (≥1 / 1000, <1/100); rare (≥1 / 10,000, <1/1000); very rare (<1/10000); unknown (available data to determine the frequency of occurrence is not possible).
Blood system: very rarely – anemia, leukopenia, thrombocytopenia.
Immune system: rare – anaphylaxis, urticaria, angioedema.
CNS: often – headache, dizziness; very seldom – agitation, confusion, tremor, ataxia, dysarthria, hallucinations, psychotic symptoms, convulsions, somnolence, encephalopathy, coma.
On the part of the respiratory system: rarely – shortness of breath.
On the part of the gastrointestinal tract and biliary system: often – nausea, vomiting, diarrhea, abdominal pain; rarely – reversible increases in bilirubin and liver enzymes; very rarely – hepatitis, jaundice.
Of the skin and its appendages: often – itching, rashes (including photosensitivity); infrequently – accelerated, generalized alopecia. Since generalized alopecia can be caused by many diseases and the use of a plurality of drugs, its relation with the action of acyclovir is not recognized apparent.
On the part of the kidney and urinary tract: rarely – increased levels of creatinine and urea in serum; very rarely – acute renal failure, renal colic, crystalluria.
Other: fatigue, fever.
Individual intolerance. Admissibility of pregnancy and breast kvrmlenii remains poorly understood.
Probenecid slows down (blocking tubular secretion). When applied topically atsiklovira not observed interactions with other drugs.